See if you can find out how far apart the rest stops are, then figure out whether you will need water between stops. That's definitely an issue on some century rides. If you think you'll need more water between stops than you normally carry, then you'll either need to plan to carry more water (hydration pack or bottles mounted on the seatpost or handlebars), or find out whether there's a public park or a convenient store where you can refill.

Good luck and have fun!